Subduction is among the most significant, yet enigmatic processes shaping our planet. Volcanism in oceanic and continental arcs is but one manifestation of major chemical exchange between the crust and mantle. Adding a precise temporal framework to this volcanic activity is a challenge rewarded by unique insights about the timing and rates of magmatic processes and the ways that volcanoes grow and erode. Moreover, these lava flows and tephras commonly contain valuable archives of global changes in the Earth's magnetic field and climate.

My research efforts are focused on the origin and evolution of arc magma, the timing and longevity of geomagnetic polarity reversals recorded by lava flows, and Quaternary paleoclimate in the southern hemisphere. Current projects involve geologic mapping and sample collection in the field, geochemical and isotopic characterization of volcanic rocks and their phenocrysts, paleomagnetic analysis, and dating using 40Ar/39Ar or cosmogenic surface exposure methods. Technological advances now poise the 40Ar/39Ar dating method to revolutionize the timescale for Pleistocene and even Holocene volcanism.

The WiscAr Geochronology Laboratory under my direction houses equipment for both radioisotopic dating using 40Ar/39Ar methods and surface exposure dating using cosmogenic helium. The principal focus of research is on Quatenary volcanism. However, the versatility and precision of the 40Ar/39Ar geochronometer is being extended toward problems in structural geology, tectonics, sedimentary basin evolution, economic geology and petrology through collaboration with many Departmental and external faculty. 

Teaching

Geoscience 610: Geochronology, Timescales, & Rates of Geological Processes

Geoscience 771: Igneous Petrology for graduate students

Geoscience 370: Introductory Petrology

Geoscience 875, Graduate Research Seminars on igneous processes

Current Graduate Students

Nathan Andersen

Allen Schaen

Paola Martinez